Hey, i've never seen a single way around this. Mainly because you have a middleman style page, is there any way to consolidate the pages into one?
Either that or checking the referring url to see if it was the referred to page:
Code:
<?
if($_SERVER['HTTP_REFERER']=="http://www.whatever.com/products6.htm")**
//go to the previous page...
}
?>
Then again if you have multiple pages you're coming from then that's going to be a little more effort.
Cheers,
Jamey